The combined effects of sulpyrin, N-acetyl-p-aminophenol and aspirin in analgesic action and acute toxicity or LD50 were studied, using male mice (dd strain), weighing 18-20g, as the test animals, fed on a solid diet and tap water given freely in an air-conditioned room of 22-23° and a relative humidity of 60%. A graphic method was used in order to analyze the combined effects. It was found that analgesic activity was potentiated but acute toxicity was considerably reduced by the combined administration of three analgesics. The graphic method described in this paper seems to be useful for analyzing the combined effect of drugs.
